The present invention relates to an improved work feed device for sewing machines, comprising feed dogs, the main feed dog and the differential feed dog, wherein the path of movement of the feed dog or dogs is elliptical.
Feed devices having an elliptical trajectory are already known, but these have the defect that the trajectory has its major axis inclined relative to the work plane of the machine, with the consequence that the dog or dogs acts or act on the foot with a thrust such that maintenance of its contact with the work is not ensured and incorrect feed of the work may ensue.
The solution which entails this disadvantage is described, for example, in Italian patent No. 544,068. In addition, in known feed devices, the moving parts are subject to considerable wear, dismantling is difficult, and consequently, it is not easy to replace parts. These disadvantages arise not only in the case of the patent referred to above, but also in the case of U.S. Pat. No. 2,442,647.